Running Hyperledger Besu instance on EC2

I'm trying to start a node for a private implementation of Besu on my EC2 instance. However, every time I try to start the node, it throws a java.net.ConnectException immediately on start. There is no message given, no cause, just throws the exception immediately and dies.

I've checked the security groups, and all the necessary ports are open. I tried it with and without UFW and no success. I also tried using ports that are already standard defined but not commonly used UDP/TCP ports, and that did not work either. It runs successfully in our local dev environment, so I know the difference is environmental and not a code issue, but I'm not sure where else to look.

The Java version is the same, the compiled jars are the same, and I've tried everything I can think of with regards to opening ports on the EC2 instance.